Let A', B', C' be the reflections of A, B, C on the opposite sides. The lines BC', B'C, AO concur at A", and A'A" is parallel to the Euler line (r380.fig)
More generally, the points A, B, C, A', B', C', A", B", C", the circumcenter O, the orthocenter H and the infinite point of the Euler line define a desmic structure. (r380_1.fig)

(r380.fig)